1. Field of the Invention
The present invention relates to improvements in or relating to a packing machine which is capable of intermittently packing desired goods by the use of a strip-like bag material made of a collapsed film tube of a thermoplastic synthetic resin such as vinyl or polyethylene.
The strip-like bag material which is ususally used in packing machines of the type described above is of the structure as illustrated in FIG. 1. The illustrated strip-like bag material F comprises a series of interconnected bag sections B which are formed by heat-sealing the collapsed film tube transversely across the same at regular intervals so as to form their respective bottoms 6 and by heat-cutting one side of the tube transversely across the same so as to form their respective opening portions 3 along and adjacent to the bottoms 3. The strip-like bag material F having a series of interconnected bag sections B is wound into the form of a roll as shown in FIG. 1 and loaded on a roll support 2 of the packing machine 10 as shown in FIG. 2.
However, in case where a packing machine of the type described above is provided with heat-sealing means and heat-cutting means for forming a bag section at the leading end of the collapsed film tube, the tube is used as a bag material as it is instead of the aforementioned ready-made bag material F.
2. Description of the Prior Art
In a conventional packing machine such as shown in FIG. 2, a packing operation with the use of the strip-like bag material F is performed as described below. First, the bag material F is pinched between a pair of intermittently operated pinching rollers 11 after being passed over guide rollers 7 in such a way that its leading end depends from the pinching rollers 11. Then the bag material F is conveyed, by actuating the pinching rollers 11, for a distance corresponding to the length of one single bag so as to locate the opening portion 3 of the foremost bag section B between a pair of heat-sealers 12a, 12b, then during an inoperative interval of the rollers 11, the foremost bag B is inflated by actuating an air blower 4 so that goods 8 can be smoothly supplied into the foremost bag B through a hopper 5. After the goods have been supplied to the bag, operation of the blower 4 is stopped and the bag is sealed along its opening portion 3 by means of the heat-sealers 12a, 12b and finally, the goods-charged bag B is separated from the subsequent bag B of the bag material F. Thereafter, such packing operation is repeated by operating the pinching rollers 11.
During the packing operation by the conventional packing machine, goods are filled into the foremost bag B depending substantially vertically along an upright frame part 13 which also serve as a guide plate for the dependent bag and accordingly, the bag tends to be deformed as a whole, as illustrated in FIGS. 2 and 3, by the weight of the goods therein, especially when the goods are small articles such as parts of machinery, electronics elements, granular articles etc.. Such deformation inevitably causes the opening portion 3 of the bag to be irregularly opened, as shown in FIG. 3, thus causing incorrect or incomplete sealing of the opening portion 3 by the heat-sealers 12a, 12b.